Safety helmet



FIG. 1 is a perspective view of a safety helmet, showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left-side elevation view thereof;

FIG. 5 is a right-side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The dashed broken lines shown in the drawings depict portions of the safety helmet that form no part of the claimed design. 

CLAIM The ornamental design for a safety helmet, as shown and described. 